A NOVEL REACTION OF A NITRO SUGAR WITH ALCOHOLS

Abstract

In connection with degradative work being undertaken in this laboratory, 3amino-3-deoxy-D-heptoses are required as reference compounds. In contrast to the abundant literature on their lower carbon analogues, relatively few syntheses of amino heptoses have been elaborated. Baschang1 has demonstrated the applicability of the nitromethane synthesis2 to this problem by the isolation of what was considered to be methyl 3-deoxy-4,6-0-ethylidene-3-nitro-D-glycero-D-mannoheptoside as the sole product from the nitromethane cyclization of periodate-oxidized methyl 4,6-O-ethylidene-a-D-glucopyranoside. We have investigated the reaction of periodate-oxidized methyl 4,6-0-benzylidene-a-D-glucopyranoside with nitromethane and have isolated four isomeric methyl 3-deoxy-3-nitro-a-D-heptosides with elementary analyses corresponding to the calculated values: (1) mp 233234?, [a]20D +37.50 (c 1, methanol); (2) mp 181-1820, [a]20D +65.5? (c 1, methanol); (3) mp 191-192?, [a]20D +750 (c 1, methanol); and (4) mp 186-1880 dec, [a]V0D +20? (c 1, methanol). The first three isomers have been reduced to crystalline amino compounds which, on oxidation with sodium metaperiodate, were found to consume rapidly (within ten minutes) 1.8-1.9 moles of oxidant per mole of amine; thereafter a slow overoxidation occurred. Isomer (3), on reduction and complete hydrolysis with acid, yielded a crystalline 3-amino-3-deoxyheptose hydrochloride. Work is in progress to obtain the 3-amino-3-deoxyheptoses from the other isomers and to establish their configurations. Details will be published elsewhere. In the course of this work, a novel reaction was encountered which we report here in detail. General.-Melting points were determined with a Hoover Unimelt apparatus and are uncorrected. Infrared spectra were measured with a Perkin-Elmer Infracord infrared spectrometer. Nuclear magnetic resonance (NMR) spectra were determined with a Varian A-60 spectrometer using tetramethylsilane as internal standard. Mass spectra were determined with an A. E. I. MS-9 spectrometer by Dr. R. Foltz of Battelle Memorial Institute. Microanalyses were performed by W. N. Rond. X-ray powder diffraction data give interplanar spacing in AO for CuKa radiation. Relative intensities were estimated visually: s, strong; m, moderate; w, weak; v, very. The strongest lines are numbered (1, strongest); double numbers indicate approximately equal intensities. Thin-layer chromatography was effected on silica gel G (E. Merck, Darmstadt, Germany) activated at 1100 using concentrated sulfuric acid to locate spots. Column chromatography was performed on silica gel grade 950 (Grace-Davison, Baltimore, Md.). Reaction of isomer (3) with methanol: (i) A solution of (3) (1 gm) in absolute methanol (50 ml) was allowed to stand at room temperature for several months. Crystals began to appear after three weeks and crystallization was judged to be complete after six months. The product was recrystallized from methanol to give methyl 4,6-0-benzylidene-3-deoxy-2,4-di-O-methyl-3-nitro-a-D-heptoside (0.89 gm,